Base stations with structure of Radio Equipment Control node (REC) and Radio Equipment node (RE) has been widely used in wireless systems. An organization named Common Public Radio Interface (CPRI) defined specifications (such as V4.2) for key internal interfaces between REC and RE.
REC usually contains radio function of digital baseband domain, and is usually related to network interface transport, radio base station control and management, as well as digital baseband processing. RE usually provides analogue and radio frequency functions, such as filtering, modulation, frequency conversion and amplification.
According to the specifications of CPRI, several types of line bit rate are available in order to achieve the required flexibility and cost efficiency: 614.4 Mbit/s, 1228.8 Mbit/s, 2457.6 Mbit/s, 3072.0 Mbit/s, 4915.2 Mbit/s, 6144.0 Mbit/s, and 9830.4 Mbit/s. Other line bit rates may be available in the future.
In current network topology, REC usually connects to RE which supports the same line bit rate as REC. Because the CPRI specifications can provide seven types of line bit rate and require that each REC and RE support at least one of the seven types of line bit rate, it will be a long term that REC and RE with different CPRI line bit rate exist in the radio system or wireless system at the same time and it is inescapable that REC connect to RE with different line bit rate. According to current solutions, when REC connects to RE with different line bit rate, they will work under lower line bit rate of both.
For example, as indicated in FIG. 1, when REC with 4915.2 Mbit/s line bit rate connects to RE with 2457.6 Mbit/s line bit rate, REC and RE will work under the 2457.6 Mbit/s line bit rate and REC will waste half of highest physical channel processing capability and part of baseband processing capability. In another example, when REC with 2457.6 Mbit/s line bit rate connect to RE with 4915.2 Mbit/s line bite rate, REC and RE will work under the 2457.6 Mbit/s line bit rate and RE will waste half of highest physical channel processing capability and carrier processing capability.
Thus, the problem is, when REC connect to RE with different line bit rate, REC and RE will work under the lower line bit rate and either REC or RE can not work with its highest processing capability and result in the waste of cost and efficiency.